The Democrats' strategy for keeping the White House was thrown into chaos last night by a "disastrous" debate performance from Joe Biden, who despite seven days' careful preparation stumbled frequently and occasionally appeared to lose his train of thought altogether. Donald Trump, unchallenged by his rival as he repeated now-familiar lies about his political and criminal record, was the clear winner in a snap post-debate poll. A senior Democrat source who had watched the debate with fellow party officials told the NYT's Peter Baker Biden would now face a "crescendo" of calls to step aside. "Joe had a deep well of affection among Democrats," the source said. "It has run dry." Biden was able to use a few prepared lines – he said Trump had the morals of an alley cat – but was hoarse and hesitant throughout. At one point Trump said: "I really don't know what he said at the end of that sentence. I don't think he knows either." Democrat strategists believe only Biden's wife, Jill, and sister Valerie, could persuade him to step down. For now the party is putting on a brave face in public but in private it is panicking.